What is "mustaali"

The Mustā‘lī are a sect of Isma'ilism named for their acceptance of al-Musta'li as the legitimate nineteenth Fatimid caliph and legitimate successor to his father, al-Mustansir Billah. In contrast, the Nizari—the other living branch of Ismailism, presently led by the Aga Khan IV—believe the nineteenth caliph was al-Musta'li's elder brother, Nizar. Isma'ilism is a branch of Shia Islam.

The Musta'li originated in Fatimid-ruled Egypt, later moved its religious center to Yemen, and gained a foothold in 11th-century North India through missionaries.